// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/wm/core/shadow_controller.h"

#include <utility>

#include "base/command_line.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/linked_ptr.h"
#include "base/scoped_observer.h"
#include "ui/aura/client/aura_constants.h"
#include "ui/aura/env.h"
#include "ui/aura/env_observer.h"
#include "ui/aura/window.h"
#include "ui/aura/window_observer.h"
#include "ui/base/ui_base_types.h"
#include "ui/compositor/layer.h"
#include "ui/wm/core/shadow.h"
#include "ui/wm/core/shadow_types.h"
#include "ui/wm/core/window_util.h"
#include "ui/wm/public/activation_client.h"

using std::make_pair;

namespace wm {

namespace {

    ShadowType GetShadowTypeFromWindow(aura::Window* window)
    {
        switch (window->type()) {
        case ui::wm::WINDOW_TYPE_NORMAL:
        case ui::wm::WINDOW_TYPE_PANEL:
        case ui::wm::WINDOW_TYPE_MENU:
        case ui::wm::WINDOW_TYPE_TOOLTIP:
            return SHADOW_TYPE_RECTANGULAR;
        default:
            break;
        }
        return SHADOW_TYPE_NONE;
    }

    bool ShouldUseSmallShadowForWindow(aura::Window* window)
    {
        switch (window->type()) {
        case ui::wm::WINDOW_TYPE_MENU:
        case ui::wm::WINDOW_TYPE_TOOLTIP:
            return true;
        default:
            break;
        }
        return false;
    }

    Shadow::Style GetShadowStyleForWindow(aura::Window* window)
    {
        return ShouldUseSmallShadowForWindow(window) ? Shadow::STYLE_SMALL : (IsActiveWindow(window) ? Shadow::STYLE_ACTIVE : Shadow::STYLE_INACTIVE);
    }

    // Returns the shadow style to be applied to |losing_active| when it is losing
    // active to |gaining_active|. |gaining_active| may be of a type that hides when
    // inactive, and as such we do not want to render |losing_active| as inactive.
    Shadow::Style GetShadowStyleForWindowLosingActive(
        aura::Window* losing_active,
        aura::Window* gaining_active)
    {
        if (gaining_active && aura::client::GetHideOnDeactivate(gaining_active)) {
            aura::Window::Windows::const_iterator it = std::find(GetTransientChildren(losing_active).begin(),
                GetTransientChildren(losing_active).end(),
                gaining_active);
            if (it != GetTransientChildren(losing_active).end())
                return Shadow::STYLE_ACTIVE;
        }
        return Shadow::STYLE_INACTIVE;
    }

} // namespace

// ShadowController::Impl ------------------------------------------------------

// Real implementation of the ShadowController. ShadowController observes
// ActivationChangeObserver, which are per ActivationClient, where as there is
// only a single Impl (as it observes all window creation by way of an
// EnvObserver).
class ShadowController::Impl : public aura::EnvObserver,
                               public aura::WindowObserver,
                               public base::RefCounted<Impl> {
public:
    // Returns the singleton instance, destroyed when there are no more refs.
    static Impl* GetInstance();

    // aura::EnvObserver override:
    void OnWindowInitialized(aura::Window* window) override;

    // aura::WindowObserver overrides:
    void OnWindowPropertyChanged(aura::Window* window,
        const void* key,
        intptr_t old) override;
    void OnWindowBoundsChanged(aura::Window* window,
        const gfx::Rect& old_bounds,
        const gfx::Rect& new_bounds) override;
    void OnWindowDestroyed(aura::Window* window) override;

private:
    friend class base::RefCounted<Impl>;
    friend class ShadowController;
    friend class ShadowController::TestApi;

    typedef std::map<aura::Window*, linked_ptr<Shadow>> WindowShadowMap;

    Impl();
    ~Impl() override;

    // Forwarded from ShadowController.
    void OnWindowActivated(ActivationReason reason,
        aura::Window* gained_active,
        aura::Window* lost_active);

    // Checks if |window| is visible and contains a property requesting a shadow.
    bool ShouldShowShadowForWindow(aura::Window* window) const;

    // Returns |window|'s shadow from |window_shadows_|, or NULL if no shadow
    // exists.
    Shadow* GetShadowForWindow(aura::Window* window);

    // Updates the shadow styles for windows when activation changes.
    void HandleWindowActivationChange(aura::Window* gaining_active,
        aura::Window* losing_active);

    // Shows or hides |window|'s shadow as needed (creating the shadow if
    // necessary).
    void HandlePossibleShadowVisibilityChange(aura::Window* window);

    // Creates a new shadow for |window| and stores it in |window_shadows_|.  The
    // shadow's bounds are initialized and it is added to the window's layer.
    void CreateShadowForWindow(aura::Window* window);

    WindowShadowMap window_shadows_;

    ScopedObserver<aura::Window, aura::WindowObserver> observer_manager_;

    static Impl* instance_;

    DISALLOW_COPY_AND_ASSIGN(Impl);
};

// static
ShadowController::Impl* ShadowController::Impl::instance_ = NULL;

// static
ShadowController::Impl* ShadowController::Impl::GetInstance()
{
    if (!instance_)
        instance_ = new Impl();
    return instance_;
}

void ShadowController::Impl::OnWindowInitialized(aura::Window* window)
{
    observer_manager_.Add(window);
    SetShadowType(window, GetShadowTypeFromWindow(window));
    HandlePossibleShadowVisibilityChange(window);
}

void ShadowController::Impl::OnWindowPropertyChanged(aura::Window* window,
    const void* key,
    intptr_t old)
{
    if (key == kShadowTypeKey || key == aura::client::kShowStateKey) {
        HandlePossibleShadowVisibilityChange(window);
        return;
    }
}

void ShadowController::Impl::OnWindowBoundsChanged(
    aura::Window* window,
    const gfx::Rect& old_bounds,
    const gfx::Rect& new_bounds)
{
    Shadow* shadow = GetShadowForWindow(window);
    if (shadow)
        shadow->SetContentBounds(gfx::Rect(new_bounds.size()));
}

void ShadowController::Impl::OnWindowDestroyed(aura::Window* window)
{
    window_shadows_.erase(window);
    observer_manager_.Remove(window);
}

void ShadowController::Impl::OnWindowActivated(ActivationReason reason,
    aura::Window* gained_active,
    aura::Window* lost_active)
{
    if (gained_active) {
        Shadow* shadow = GetShadowForWindow(gained_active);
        if (shadow && !ShouldUseSmallShadowForWindow(gained_active))
            shadow->SetStyle(Shadow::STYLE_ACTIVE);
    }
    if (lost_active) {
        Shadow* shadow = GetShadowForWindow(lost_active);
        if (shadow && !ShouldUseSmallShadowForWindow(lost_active)) {
            shadow->SetStyle(GetShadowStyleForWindowLosingActive(lost_active,
                gained_active));
        }
    }
}

bool ShadowController::Impl::ShouldShowShadowForWindow(
    aura::Window* window) const
{
    ui::WindowShowState show_state = window->GetProperty(aura::client::kShowStateKey);
    if (show_state == ui::SHOW_STATE_FULLSCREEN || show_state == ui::SHOW_STATE_MAXIMIZED) {
        return SHADOW_TYPE_NONE;
    }

    const ShadowType type = GetShadowType(window);
    switch (type) {
    case SHADOW_TYPE_NONE:
        return false;
    case SHADOW_TYPE_RECTANGULAR:
        return true;
    default:
        NOTREACHED() << "Unknown shadow type " << type;
        return false;
    }
}

Shadow* ShadowController::Impl::GetShadowForWindow(aura::Window* window)
{
    WindowShadowMap::const_iterator it = window_shadows_.find(window);
    return it != window_shadows_.end() ? it->second.get() : NULL;
}

void ShadowController::Impl::HandlePossibleShadowVisibilityChange(
    aura::Window* window)
{
    const bool should_show = ShouldShowShadowForWindow(window);
    Shadow* shadow = GetShadowForWindow(window);
    if (shadow) {
        shadow->SetStyle(GetShadowStyleForWindow(window));
        shadow->layer()->SetVisible(should_show);
    } else if (should_show && !shadow) {
        CreateShadowForWindow(window);
    }
}

void ShadowController::Impl::CreateShadowForWindow(aura::Window* window)
{
    linked_ptr<Shadow> shadow(new Shadow());
    window_shadows_.insert(make_pair(window, shadow));
    shadow->Init(GetShadowStyleForWindow(window));
    shadow->SetContentBounds(gfx::Rect(window->bounds().size()));
    shadow->layer()->SetVisible(ShouldShowShadowForWindow(window));
    window->layer()->Add(shadow->layer());
}

ShadowController::Impl::Impl()
    : observer_manager_(this)
{
    aura::Env::GetInstance()->AddObserver(this);
}

ShadowController::Impl::~Impl()
{
    DCHECK_EQ(instance_, this);
    aura::Env::GetInstance()->RemoveObserver(this);
    instance_ = NULL;
}

// ShadowController ------------------------------------------------------------

ShadowController::ShadowController(
    aura::client::ActivationClient* activation_client)
    : activation_client_(activation_client)
    , impl_(Impl::GetInstance())
{
    // Watch for window activation changes.
    activation_client_->AddObserver(this);
}

ShadowController::~ShadowController()
{
    activation_client_->RemoveObserver(this);
}

void ShadowController::OnWindowActivated(ActivationReason reason,
    aura::Window* gained_active,
    aura::Window* lost_active)
{
    impl_->OnWindowActivated(reason, gained_active, lost_active);
}

// ShadowController::TestApi ---------------------------------------------------

Shadow* ShadowController::TestApi::GetShadowForWindow(aura::Window* window)
{
    return controller_->impl_->GetShadowForWindow(window);
}

} // namespace wm
